Project IRENE Using optical scanning to digitize ethnographic field recordings on wax cylinders

Comparing Optical and Stylus Transfers: Resolution Limits

This Diagram schematizes the resolution limits of a hard stylus. The colored lines represent signals at different frequencies. They increase in frequency and decrease in wavelength as they move down the page. The stylus can only fit into and follow the light blue line, which has the smallest frequency and a wavelength equal to around twice the stylus's diameter. The stylus could not follow and resolve the other signals without attenuation. A method of reading the signals that had a smaller width, such as a light spot with a 10 micron diameter, like the light points measured by the optical probe, can fit into and resolve much smaller higher frequency, more tightly spaced signals.
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diagram and method